Mitt Romney on Wednesday contradicted his earlier statement and said the individual mandate was a tax after all. Photograph: Jessica Rinaldi/Reuters

Mitt Romney's contradictory statements on whether the Obama administration's health care reforms amount to a tax have drawn heavy criticism from both sides of the political divide.

The Wall Street Journal editorial board, normally a staunch supporter of Republican causes, published an excoriating attack on Romney and his inner campaign circle on Wednesday. The paper said that Romney's contortions over healthcare reform had left his campaign looking confused and politically dumb.

"Mr Romney promised Republicans he was the best man to make the case against President Obama, whom they desperately want to defeat. So far Mr Romney is letting them down," the editorial article said.

President Obama's campaign team accused Romney of coming under pressure from the "extreme right" of the Republican party after he performed an about-turn over the nature of the individual mandate, which requires individuals who can afford it to buy health insurance. Obama's re-election campaign spokeswoman, Jen Psaki, told reporters aboard Air Force One as they travelled with the president at the start of a two-day trip to Ohio that Romney had been struck by "the push from the right, the Rush Limbaughs of the world, [and] congressional Republicans, who are pushing him to go back on a decision and a defence that he's had in place for years".

Romney's difficulties stem from his tortured reponse to the supreme court's ruling on the Affordable Care Act, dubbed "Obamacare". The court declared the act to be constitutional, concluding that the federal government had the power to require individuals to buy health insurance under its tax-raising powers.

Republican leaders across the country seized on the ruling, saying that it proved that Obama was increasing the tax load of ordinary Americans. But Romney went in the opposite direction, arguing through his adviser Eric Fehrnstrom on Monday that the individual mandate was not a tax, but a penalty.

However, on Wednesday, Romney made an abrupt U-turn, contradicting his earlier position and saying the individual mandate was a tax after all. In a hastily called TV interview with CBS from his holiday home in New Hampshire, he said: "The supreme court has the final word. And their final word is that Obamacare is a tax. So it's a tax."

Romney's very public struggle over how to define the individual mandate has been politically damaging because it chimes with several of his perceived weaknesses as a presidential candidate. It speaks to the accusation that he is a flip-flopper, that dates as far back as 1994 when Ted Kennedy accused him of being "multiple choice" on the abortion issue during their battle over the senate seat for Massachusetts.

It also speaks to the core problem he has had in criticising Obamacare: the fact that the law and the individual mandate was modelled upon his own scheme that he introduced as governor of Massachusetts. Romney's initial classification of the individual mandate as a penalty and not a tax was presumably designed to avoid claims that he increased taxes – he has made it a cornerstone of his bid for the White House that he cut Massachusetts taxes 19 times while in office.

But in the outcome, his attempts to duck and dive his way through this policy conundrum has only made matters worse. It has allowed the Democrats to revel in his discomfort.

"If Tea Party and Cong Rs can pull Mitt's chain, and get him to do a 180 on the mandate he championed, imagine what they'd do with him in WH!", tweeted David Axelrod, communications chief of Obama's re-election campaign.

Among Tea Party followers and core conservatives, the debacle has also heightened suspicions that Romney is not one of them. "He certainly has tied himself in knots on this issue," said pollster and Tea Party expert Scott Rasmussen.

"The Republican base doesn't trust him, and every time he says something that makes them think he's going soft there's going to be an uproar."